Because we live in practical times, this question usually elicits practical answers. We go into space because of the benefits it produces back on earth: It provides us with better communications and a vantage point that allows us to better understand and manage the earth's natural resources. It encourages industrial development and creates high-tech jobs. It inspires students to take up careers in science and technology. It promotes international technological co-operation.

These reasons are part of the answer but not all of it. We go into space for more than practical reasons; even though it has become less fashionable to speak of them, there are deep-seated philosophical and psychological imperatives that drive us to explore beyond the boundaries that encompass us. We go into space because it speaks to two of our most deeply human traits: curiosity and the compulsion to take on great challenges.

It has been said that we climb mountains because they're there. Space is there too, a mysterious "mountain" of unimaginable, almost infinite proportions. It's an in-your-face challenge that our human nature finds impossible to ignore. No doubt from the moment humans first looked up at the stars, we wondered what they were, where they were and what else is out there. Down through the millennia, we've wondered if there are other places, other species, out there and what we'll do when we find them. We're intent on finding them, whatever and wherever they may be, for it's simply not in our nature to willfully turn away from the quest for knowledge. But indulging our curiosity, our thirst for knowledge, our need for challenge, is neither easy nor cheap. Some people find that reason enough not to try, but for many, the difficulty is precisely the point. As President John F. Kennedy said in 1962 when he committed the U.S. to reach for the moon: "We choose to go to the moon in this decade and do the other things, *not because they are easy, but because they are hard*, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone and one which we intend to win."

The ability to take on great challenges, and to learn from failure while building on success, is the hallmark of a dynamic species. Whatever practical social and economic benefits the effort affords, the underlying payoff is that *trying*, in itself, pushes the envelope of creativity and problem-solving and nurtures the skills needed to venture even further. Without the will to try, we would stagnate.

Canadian astronaut Chris Hadfield is one of only a small handful of humans who've had the privilege of seeing the earth and the stars from the vantage point of space. Reflecting on the significance of the launch of Zarya, the Russian-built module that became the first component of the international space station to rise into space, Hadfield described it as "a triumph of hope over history, of will over won't, and of optimism over cynicism. For the first time in history, we had blasted off from Earth as one nation of human beings. Not in competition with each other, not for short term profit, not to bounce TV signals to each other, not to spy on each other, but as the first step in permanently leaving Earth together. As one world, we have successfully climbed off our mother planet's knee, and have begun to venture forth into the limitless possibilities of the universe."

It is fitting, he says, that this millennium is ending with the start of "an amazing new era-the Interplanetary Age." He sees Zarya, and the space station it will grow into, as a "portal to the future, and we have begun to step through. It flies in the face of historical conflict. It flies in the face of human jealousy and competition. It flagrantly flies in the face of cynicism, apathy and the daily grind. But above all, it flies. Effortlessly, over our heads, Zarya floats weightless - waiting for the future to unfold."

We still have a long way to go. If we mark its start from the launch of Sputnik in 1957, the space age has not yet spanned a single human lifetime. Despite what we've accomplished in that short time, we are, as a space-faring species, still mere children, barely able to manage more than camping out in the backyard. Yet, like young children, we excitedly explore every new marvel of our rapidly expanding universe, finding in each new phenomenon something to fire our imagination and prompt yet more questions.

In the process, we're acquiring the knowledge and survival skills needed to carry us down the road that leads away from home. Like all children, we'll leave home eventually and the fact that the world awaiting us is vast, mysterious and undoubtedly dangerous is not an obstacle - it's what draws us on. We've always been driven to test our mettle against the unknown and to unravel the complexities that nature and the universe place before us. In the end, it is this trait more than any other that has produced the greatest practical benefits that science and technology have brought us.

That it has also produced some of our worst mistakes, such as weapons of mass destruction and the ability to ravage the earth's environment, is a reality we should ponder as we stand poised on the threshold of space. Managing the fruits of our curiosity wisely has become, in itself, one of our greatest challenges. We face an unparalleled opportunity to meet that challenge by orchestrating a united and peaceful migration into space.